1. Field of Invention
The present invention relates to an endoscope for intubating an endotracheal tube which enables optical observation of a patient's body cavity so that an operator can easily intubate the endotracheal tube into a patient who suffers from difficulty in breathing because of a sudden onset of a disease or an injury at the scene of an accident, disaster, or a like occurrence and whose airway must be ensured urgently. More specifically, the present invention relates to the structure of a bending operation section of a portable endoscope for intubating an endotracheal tube, and the endoscope as well enables use of a light source or a power source in combination therewith so as to enable immediate medical response at the scene of an accident or disaster. More specifically, the present invention relates to the structure of an operation portion of a portable endoscope for intubating an endotracheal tube.
2. Related art
A conventionally-practiced method for intubating an endotracheal tube into a patient's body comprises a step of inserting a stylet or an endoscope, which has a bending function, into the internal space of an endotracheal tube and fixing the thus-inserted stylet or endoscope; and a step of intubating the endotracheal tube into the patient's body and guiding the distal end of the endotracheal tube to the larynx by the bending function of the stylet or endoscope, or a step of intubating an endotracheal tube into a trachea while the stylet or endoscope is used as a guide, after direct visual checking of the trachea, and retaining the thus-intubated endotracheal tube in place. One example of the stylet is described in U.S. Pat. No. 4,529,400, and one example of the endoscope is described in Japanese Patent Application Laid-Open No. Hei-9-238897.
In practice, these devices encounter various problems in use. One of the problems is that an operator cannot directly and manually feel the resistance against the endotracheal tube when being intubated into the human body.
In this type of medical device, an insertion portion of the stylet or endoscope is inserted into the internal space of the endotracheal tube, and the insertion portion of the stylet or endoscope is intubated into the human body while being fixed with the endotracheal tube. In the conventional device, a bending operation piece, such as a bending leer or knob, of a bending operation mechanism is provided at a position where the operation piece is to be actuated by the hand that is holding the operation section of the stylet or endoscope. If an attempt is made to hold the endotracheal tube directly by hand, the operator cannot perform a bending operation. For this reason, the operator must intubate the endotracheal tube while holding the operation section. The endotracheal tube has flexibility, whereas the operation section of the stylet or endoscope is rigid. Even if the endotracheal tube is fixedly attached to the stylet or endoscope, the operator cannot feel subtle resistance against the endotracheal tube while being intubated into the patient's body, by way of the hand that is holding the operation section. For this reason, there exists a danger of damaging the wall of a body cavity by forceful intubation of the endotracheal tube.
The operator intubates the endotracheal tube into the patient's body by holding a laryngoscope in, for example, the left hand, to thereby forcefully open the mouth, and by inserting the endotracheal tube equipped with the stylet or endoscope by the right hand while holding the operation section of the stylet or endoscope.
When the endotracheal tube can be inserted by a short distance into the trachea, only the stylet or endoscope is withdrawn. If the stylet or endoscope remains within the endotracheal tube, the entire endotracheal tube has high rigidity. If the endotracheal tube is intubated, exactly as is, the wall of the body cavity may be damaged. For this reason, the rigidity of the endotracheal tube is diminished by only the endotracheal tube being left in the trachea.
Since the endotracheal tube is situated a short distance inside the trachea, it will be forced out by the tongue unless the previously-described operations are performed while the tongue is lifted up by the laryngoscope. Therefore, the operator's left hand is occupied with lifting up the tongue, and only his right hand is available. However, if the operator attempts to lift up the tongue with his right hand, he must release his right hand from the operation section of the stylet or endoscope and hold the endotracheal tube.
If the hand is released from the operation section, the operation section will fall under its own weight and the entire endotracheal tube will be pulled out from the trachea. In order to avoid this, the operator must shift his hand while an assistant supports the endotracheal tube or the operation section. These operations involve stationary and fixed supporting of the endotracheal tube. If shifting of the hand fails for poor coordinated operation or the endotracheal tube is moved during the shifting of the hand, the endotracheal tube is pulled out from the trachea.
Further, in practice, the intubating operation in connection with this method involves various problems. One of the problems is that the length of the insertion portion changes when the endoscope is bent. According to the conventional method, the endoscope is usually intubated into the patient's body while the distal end of the endoscope remains a slight distance short of the distal end of the endotracheal tube. In many cases, the endoscope is to be used for a patient whose larynx is bleeding because of injury. In such a case, if the endoscope is intubated together with the endotracheal tube while the distal end of the endoscope sticks out from the distal end of the endotracheal tube, an objective lens attached to the distal end of the endoscope is stained with blood and becomes unable to acquire images. However, if the endoscope remains far short of the distal end of the endotracheal tube, the interior wall of the endotracheal tube occupies the field of view of the endoscope, thus limiting the field of view of the operator and preventing the operator from acquiring a wide-range view of the trachea. Accordingly, the operator encounters difficulty in searching an area of interest. For these reasons, the distal end of the endoscope is set in the manner as mentioned above; the distal end of the endoscope remains a slight distance short of the distal end of the endotracheal tube such that the interior wall of the endotracheal tube does not appear within the field of view of the endoscope.
Since the endotracheal tube is sturdy, a considerable amount of force is required to bend the endoscope during intubation of the endotracheal tube. For this reason, the endoscope has a structure which is relatively sturdy and enables strong bending action. In one example of such a structure, an insertion portion is formed at the distal end of the endoscope by connection of a resin tube to the distal end. A wire is connected to a position on the distal end of the endoscope or on the distal end of the resin tube, the position being radially offset from the center axis through which the endoscope is to be inserted. The endoscope is bent when the operator withdraws the wire. In another example of the structure, a resin tube is connected to the distal end of the endoscope, and a bend-recovery part formed from a coil spring or a like spring is attached to the distal end of the resin tube. In the case of the previously-described example, the wire is attached to the distal end of the endoscope, the distal end of the resin tube, or the distal end of the bend-recovery part. The endoscope is bent in a recovery manner when the operator withdraws the wire.
However, in such a structure, the wire is directly or indirectly fixed to the distal end of the endoscope. The force exerted to withdraw the wire also acts as force to withdraw the distal end of the endoscope, thereby compressing the insertion portion. Consequently, the insertion portion meanders or becomes contracted, thus resulting in a previously-described problem of the length of the insertion portion changing.
In this case, the distal end of the endoscope located within the endotracheal tube is withdrawn excessively far, and the interior wall of the endotracheal tube appears within the field of view of the endoscope, thus limiting the field of view of the operator and making it difficult for the operator to search an area of interest. The operator must control the amount by which the endoscope is to be inserted into the endotracheal tube so as to prevent the interior wall of the endotracheal tube from appearing within the field of view of the endoscope. Further, even when the amount has been properly readjusted, if the extent to which the endoscope is bent is diminished, the endoscope is extended, as a result of which the distal end of the endoscope sticks out from the endotracheal tube. In this event, blood or other substance adheres to the objective lens provided at the distal end of the endoscope, thereby rendering the endoscope unable to acquire images Performing such operations in an emergency situation is troublesome.
Another problem is that the insertion portion of the endoscope becomes twisted when the endoscope is bent. The endotracheal tube is given a tendency to bend in a certain direction, in order to facilitate intubation of the endotracheal tube into the patient's trachea. If the endoscope inserted in the endotracheal tube will not bend in the same direction in which the endotracheal tube tends to bend, the endotracheal tube may be intubated into an unexpected direction and fail to advance into the trachea, because the endotracheal tube is intubated while the endoscope serves as a guide.
In order to cope with such a problem, the endoscope is inserted into the endotracheal tube such that the direction in which the endotracheal tube tends to bend matches the direction in which the endoscope tends to bend. However, in some cases the endoscope does not bend in the direction in which it is normally bent. These cases include the case where the wire is slightly offset from the position where it is to be fixed, and the case where the residual torsion is present in a resin tube which serves as a sheath of the insertion portion. Since an elastic member used for the endotracheal tube or the endoscope-such as a resin tube or a coil spring-assumes a circular cross section, force for limiting torsion does not act on the elastic member. Since such an elastic member can bend in any direction, the previously-described problem inevitably arises.
Moreover, a portable endoscope for intubating an endotracheal tube to be used in combination with a compact power supply or light source has been conceived as an endoscope for quickly intubating the endotracheal tube into a patient's body at the scene of an accident or disaster.
In this portable endoscope, a compact lamp is used as the light source, and dry batteries or compact rechargeable batteries are used as the power supply. The light source and the power supply are incorporated into the operation portion or are removably attached to the outer sheath of the operation portion. In another type of endoscope, because even a compact power supply has a certain volume and weight, the power supply is provided separately from the endoscope, or both the power supply and the light source are separately from the endoscope. When the endoscope is in use, the power supply and the light source are connected to the operation portion by cables and are carried by or placed near the operator.
When the light source and the power supply are provided within the operation portion or removably attached to the outer sheath of the operation portion, consideration is given to determining locations for the light source and the power supply. If the light source and the power supply are provided in a grip of the operation portion, the grip will eventually become bulky for manual handling.
For this reason, the light source and the power supply are usually provided in a portion of the endoscope close to the operator.
Generally, an eyepiece section for optically observing the interior of the human body is provided at the portion of the endoscope close to the operator; i.e., the end of the operation portion, rather than at the grip. The light source and the power supply are usually provided in the vicinity of the eyepiece section.
When the light source and the power supply are provided at such a location and the operator holds the operation portion, the weight balance of the endoscope worsens, thus making the endoscope difficult to handle.
In the endoscope, an insertion portion to be inserted into the human body is connected to one end of the operation portion, and the eyepiece section is provided at the other end of the operation portion. The grip is usually provided at the portion of the operation portion close to the insertion portion rather than at the portion close to the eyepiece section.
The insertion portion is elongated and lightweight. If the eyepiece section is heavy, the endoscope is tilted toward the eyepiece section and the insertion portion is urged upward when the operator holds the grip. The endoscope is usually inserted into the patient from above while the patient is lying on his back.
Accordingly, the endoscope is to be inserted while the insertion portion is urged to face downward. However, because of weight balance, the insertion portion is urged to face upward, and the operator must forcefully hold the endoscope with his hand such that the insertion portion faces downward. The operator must continuously hold the endoscope in that state until intubation of the endotracheal tube is completed. This imposes great difficulty on the operator. Particularly, when the operator is performing delicate operation, holding the endoscope for a long period of time imposes great difficulty.
In the case of an endoscope--whose power supply and light source are provided separately from an operation portion and which is used while the power supply and the light source--are connected to the operation handle by a cable while the endoscope is carried by the operator, the cable hinders the operator's operation at the scene of an emergency where the operator and other personnel tend to move hurriedly and unpredictably. In a case where the operator carries the light source and the power supply, his clothing may be stained with gory hands when he attempts to remove the light source and the power supply after intubation of the endotracheal tube. In a case where the operator uses the endoscope while the light source and the power supply are situated near, the operator runs the risk of touching a contaminated area, such as a ground surface, or the light source or the power supply installed on the floor, with the result that the operator may intubate the endotracheal tube with contaminated hands.